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Abstract: High pressure phase behavior of the CO2 +2-ethoxyethyl methacrylate (2-EEMA) and CO2 +2,3-epoxypropyl methacrylate (2,3-EPMA) systems has been investigated in static method at five temperatures of 313.2, 333.2, 353.2, 373.2 and 393.2K and pressures up to 21.3MPa. Both CO2 +2-EEMA and CO2 +2,3-EPMA systems have continuous critical mixture (locus) curves that exhibit maximums in pressure–temperature space between the critical temperatures of CO2 and 2-EEMA or 2,3-EPMA. The solubility of 2-EEMA and 2,3-EPMA for the CO2 +2-EEMA and CO2 +2,3-EPMA systems increases as the temperature increases at fixed pressure. The CO2 +2-EEMA and CO2 +2,3-EPMA systems exhibit type-I phase behavior. The experimental results for the CO2 +2-EEMA and CO2 +2,3-EPMA systems are correlated with Peng–Robinson equation of state using a mixing rule including two adjustable parameters. The critical properties of 2-EEMA and 2,3-EPMA are predicted with Joback–Lyderson and Lee–Kesler method. [Copyright &y& Elsevier]

Abstract: Pressure-composition (P–x) isotherms were obtained for the carbon dioxide+4-chlorostyrene (4-CS) system using static apparatus at five temperatures (313.2, 333.2, 353.2, 373.2 and 393.2K) and pressure up to 23.74MPa. The experimental results for the carbon dioxide+4-CS system were modeled with the Peng–Robinson equation of state (PR EOS) using two adjustable parameters. The comparison between the experimental results and the calculated curves shows a good agreement at five temperatures. Three phases were not observed at any five temperatures in this system. The experiments were conducted to obtain cloud-point data of binary and ternary mixture for the poly(4-chlorostyrene) [P(4-CS), Mw=87,000, Mn=57,000, polydispersity=1.53]+supercritical solvents (propane, propylene, butane and 1-butene)+acetone, the P(4-CS)+supercritical solvents [butane, 1-butene and dimethyl ether (DME)]+4-CS and the P(4-CS)+supercritical solvents (butane and 1-butene)+ethanol, the P(4-CS)+supercritical solvents (propylene, 1-butene and DME) and the P(4-CS)+carbon dioxide+DME systems. High pressure phase behavior experiment for the binary and ternary mixture of the P(4-CS)+supercritical solvents+cosolvent systems is measured within a temperatures range of 332.8–494.2K and pressure up to ca. 260.0MPa. The P(4-CS)+supercritical solvents (propane, propylene and 1-butene)+acetone systems show the changes in the pressure–temperature (p–T) curve from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as acetone concentration increases. The phase behavior curves for the P(4-CS)+supercritical solvents (butane, 1-butene)+4-CS systems of three systems [the P(4-CS)+4-CS mixture in supercritical solvents (butane, 1-butene and DME)] exhibit UCST region with negative slopes, but in the case of the P(4-CS)+DME+4-CS system, cloud-point behavior shows LCST-type curve with a positive slope. The cloud-point behaviors for P(4-CS)+supercritical solvents (butane and 1-butene)+ethanol systems exhibit USCT-type curves with negative slopes. The P(4-CS)+carbon dioxide+ x wt.% DME system shows cloud-point curves changing from UCST region to LCST region as DME concentration increases. [Copyright &y& Elsevier]

Abstract: Three different supercritical fluids, CO2, dimethyl ether (DME), and chlorodifluoromethane (CHClF2), were investigated as potential solvents for processing two (meth)acrylate polymers. High pressure phase behavior data to 505K and 265.7MPa were reported for poly(hydroxypropyl methacrylate) [PHPMA] and poly(hydroxypropyl acrylate) [PHPA] in the supercritical fluid solvents+cosolvent system. Cloud-point curves for the PHPA and PHPMA in the supercritical DME show about a 40.0MPa pressure difference of constant temperature at ∼373K. The phase behavior for the PHPMA+DME+2-hydroxypropyl methacrylate (2-HPMA) and PHPA+DME+2-hydroxypropyl acrylate (2-HPA) systems were measured from changes of the pressure–temperature curve slope, and with cosolvent concentrations of w 3 =0–0.463 (2-HPMA) and w 3 =0–0.453 (2-HPA), respectively. The PHPMA+DME+ w 3 =0.0–0.238 CO2 and PHPA+DME+ w 3 =0.0–0.210 CO2 mixture show UCST-type behavior with a negative slope, and then the pressure increases smoothly for temperatures in the range of 323–492K. PHPMA and PHPA do not dissolve in pure CO2 at a temperature of 518K and pressure of 280.0MPa. The location of the PHPMA+CO2 cloud-point curve shifts to lower temperatures and pressures when w 3 =0.40–0.66 2-HPMA was added to the PHPMA+CO2 solution. The phase behavior for the PHPA+CO2 + w 3 =0.35–0.68 2-HPA system changes the pressure–temperature curve from an upper critical solution temperature (UCST) region to a lower critical solution temperature (LCST) region as the 2-HPA concentration increases. The PHPMA+CO2 + w 3 =0.689 2-HPMA phase behavior curve intersects a fluid→liquid+vapor (LV) curve at ∼393K and ∼16.0MPa. [Copyright &y& Elsevier]